1. Field of the Invention
The present invention relates to a communication method of an electronic apparatus in which communication is performed by integrally controlling a plurality of apparatuses, such as cameras or the like.
2. Description of the Related Art
A technique of controlling electronic apparatuses, such as cameras or the like, from a personal computer (PC) using standards, such as RS-232C or the like, has been known. When using the RS-232C standards, it is impossible to control a plurality of electronic apparatuses unless a plurality of connectors are provided at a PC. In order to solve such a problem, there is a conventional method of performing communication by serially connecting a plurality of electronic apparatuses. However, in this conventional method of performing communication by serially connecting electronic apparatuses, it is necessary to provide at each of the electronic apparatuses a terminal for determining whether or not other electronic apparatuses are connected at the following stage, in addition to signal lines for transmitting/receiving control signals for the electronic apparatus.
It is an object of the present invention to provide a method for controlling an electronic apparatus in which a plurality of electronic apparatuses can be controlled while serially connecting them, without increasing the number of signal lines.
According to one aspect, the present invention is an electronic apparatus, among a plurality of serially connected electronic apparatuses, which can communicate a control command signal and first and second control signals. The electronic apparatus includes a first connection unit, having an input terminal for inputting the first control signal and an output terminal for outputting the second control signal, which is connected to an electronic apparatus provided at an immediately preceding stage of connection. A second connection unit has an output terminal for outputting the first control signal and an input terminal for inputting the second control signal, which is connected to an electronic apparatus provided at an immediately succeeding stage of connection. A processing unit has a first input terminal connected to the input terminal of the first connection unit, a second input terminal connected to the input terminal of the second connection unit, and a change-over switch for switching connection of the output terminal of the first connection unit to one of the output terminal of the processing unit and the input terminal of the second connection unit. The processing unit provides the first control signal, outputs the provided first control signal from the output terminal, determines whether or not the second control signal has been input from the second input terminal in response to the output of the first control signal, and controls the change-over switch in accordance with the determination.
According to another aspect, the present invention is an electronic apparatus, among a plurality of electronic apparatuses serially connected to a computer, which can communicate a control command signal and first and second control signals. The electronic apparatus includes a first communication unit for communicating the control command signal and the first and second control signals with an electronic apparatus provided at an immediately preceding stage of connection, a second communication unit for communicating the control command signal and the first and second control signals with an electronic apparatus provided at an immediately succeeding stage of connection. A processing unit provides the first control signal, outputs the provided first control signal to an electronic apparatus to be connected at an immediately succeeding stage of connection via the second communication unit, determines whether or not the second control signal has been input in response to the output of the first control signal, and notifies, when it has been determined that the second control signal has not been input, the computer of the fact that the concerned electronic apparatus is connected at a last stage of connection via the first communication unit.
According to still another aspect, the present invention is a computer terminal which serially connects a plurality of electronic apparatuses and which can integrally control the plurality of electronic apparatuses by communicating a control command signal and a predetermined control signal with each of the plurality of electronic apparatuses. The computer terminal includes a communication unit for communicating the control command signal and the predetermined control signal with each of the plurality of electronic apparatuses, and a processing unit for outputting the predetermined control signal to which an ID address of a computer is added, detecting whether or not a response command corresponding to the output predetermined control signal has been input, recognizing, when it has been detected that the response command has been input, a connection state of the concerned electronic apparatus based on the input response command, and providing the concerned electronic apparatus with a control command based on the recognition.
According to yet another aspect, the present invention is a communication method of an electronic apparatus, from among a plurality of electronic apparatuses serially connected to a computer, which can communicate a control command signal and first and second control signals. The method includes the steps of newly providing the first control signal in accordance with input of the first control signal output from the computer or an electronic apparatus provided at an immediately preceding stage of connection, outputting the provided first control signal to an electronic apparatus to be connected at an immediately succeeding stage of connection, determining whether or not the second control signal has been input in response to the first control signal output to the electronic apparatus to be connected to the immediately succeeding stage of connection, and notifying, when the second control signal has not been input, the computer of the fact that the concerned electronic apparatus is at a last stage of connection.
According to yet a further aspect, the present invention is an operation process of a computer terminal which serially connects a plurality of electronic apparatuses and which can integrally control the plurality of electronic apparatuses by communicating a control command signal and a predetermined control signal with each of the plurality of electronic apparatuses. The process includes a communication step of communicating the control command signal and the predetermined control signal with each of the plurality of electronic apparatuses, and a processing step of outputting the predetermined control signal to which an ID address of a computer is added, detecting whether or not a response command corresponding to the output predetermined control signal has been input, recognizing, when it has been detected that the response command has been input, a connection state of a concerned electronic apparatus based on the input response command, and providing the concerned electronic apparatus with a control command based on the recognition.
According to still another aspect, the present invention is a storage medium storing communication modules of an electronic apparatus, from among a plurality of electronic apparatuses serially connected to a computer, which can communicate a control command signal and first and second control signals. The modules include a module of newly providing the first control signal in accordance with input of the first control signal output from the computer or an electronic apparatus provided at an immediately preceding stage of connection, a module of outputting the provided first control signal to an electronic apparatus to be connected at an immediately succeeding stage of connection, a module of determining whether or not the second control signal has been input in response to the first control signal output to the electronic apparatus to be connected at the immediately succeeding stage of connection, and a module of notifying, when the second control signal has not been input, the computer of the fact that the electronic apparatus is at a last stage of connection.
The foregoing and other objects, advantages and features of the present invention will become more apparent from the following description of the preferred embodiment taken in conjunction with the accompanying drawings.